The present invention relates to structural panels, and more particularly concerns methods and apparatus that are specially useful for welding a workpiece that may be used as part of a structural panel having a core reinforced by a three-dimensional wire matrix. Various configurations employing combinations of lightweight insulative filler material, such as cellular plastic foams, and rigid load bearing structural elements have been suggested in the past for providing structural building panels that can effectively utilize desirable properties of the filler materials. Some of such prior art arrangements are shown in the U.S. patents to Weismann Nos. 3,305,991, 3,555,131 and 3,879,908.
In my co-pending application for a Structural Panel, Ser. No. 857,235, filed Dec. 5, 1977, and in my co-pending application for Method and Apparatus for Manufacture of Wire Truss and Sinuous Strut Therefor, Ser. No. 014,988, filed Feb. 26, 1979, and my co-pending application for Composite Structural Panel with Offset Core, Ser. No. 023,590, filed Mar. 26, 1979, there are described composite foam and wire matrix structural panels in which a number of twodimensional lattice structures or wire trusses and a number of elongated foam filler elements are stacked in consecutive alternation and then laterally pressed against one another to forcibly embed the trusses in the filler elements. While holding such stacked wire trusses and filler elements in laterally pressed condition, the trusses are fixedly secured to one another by means of a number of mutually spaced transversely extending cross members which are welded to the runner wires of the respective trusses. Specific configurations of those panels and certain aspects of methods of construction thereof are set forth in detail in the prior applications, the disclosures of which are incorporated by this reference as though fully set forth herein.
The present invention is concerned with methods and apparatus for welding of one wire to a number of other wires. Such methods and apparatus are uniquely adapted for the welding of cross wires of the abovedescribed stack of alternate wire trusses and foam filler elements in the manufacture of such composite structural panels. Although the methods and apparatus described herein are specifically adapted for manufacture of such panels, the apparatus and methods described herein may readily be employed for manufacture of other articles.